In a manufacturing process of a semiconductor device, ion implantation is performed on a semiconductor wafer (hereinafter referred to as a wafer) which is a substrate. This ion implantation is carried out, for example, in a state in which a mask made of a resist film is formed. The mask is removed after the ion implantation. For example, a mask for ion implantation and a method for removing the mask have been used.
As will be described in the Detailed Description section below, the aforementioned ion implantation turns the surface of a resist film, which is an organic film, into a carbonized layer having a relatively high hardness. Along with the miniaturization of wiring of a semiconductor device, there is a case where the resist film is formed to have unevenness. In that case, the aforementioned carbonized layer is also formed on the side surface of the resist film in addition to the upper surface thereof. That is to say, there is a tendency that the amount of the carbonized layer formed on the wafer increases. In order to remove the carbonized layer at the time of removing the resist film it is conceivable to perform a process (ashing) of supplying an oxygen gas in a plasma state, a process of supplying a high-temperature cleaning solution or a chemical solution having a relatively high polarity, a process of supplying an ozone gas, or the like. In either case, there is a concern that the ion implantation region which is not covered with the resist film is damaged. In addition, there is a concern that by performing the aforementioned processes, the carbonized layer is ruptured to generate particles. Since the amount of formation of the carbonized layer tends to increase as described above, there is a concern that the influence of the particles becomes large.
Therefore, a technique for performing ion implantation while preventing the formation of the carbonized layer is required. In the aforementioned removal method, a silicon-containing film is formed as a mask for ion implantation. After the ion implantation, the wafer is dipped in a mask stripping solution to remove the mask. However, in order to perform such a process, it is necessary to transfer a substrate from a vacuum atmosphere in which ion implantation is performed to an atmospheric pressure atmosphere for performing liquid processing. In this case, the number of steps increases and the cost grows higher. Moreover, the transfer of the substrate is inefficient.